Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
Trending News
Physics Help?
Light is incident of the surface of metallic sodium, whose work function is 2.3 eV. The maximum speed of the photoelectrons emitted by the surface is 2.90 × 106 m/s. What is the wavelength of the light?
1 Answer
- 4 years agoFavorite Answer
Energy of the incident equals the work function plus the induced kinetic energy of the ejected electrons
hc/w = W + 0.5mv^2 (v is small enough to use nonrelativistic KE)
0.5mv^2 = 0.5(9.1 x 10^-31)(2.90 x 10^6)^2 = 3.83 x 10^-18 J = 23.9 eV
hc/w = 2.3 + 23.9 = 26.2 eV
1240 nm eV/w = 26.2
w = 1240 nm eV/26.2 eV
w = 47.3 nm
